Headache diaries are frequently used tools for clinical management of headache patients and for research. They facilitate accurate classification of headache episodes and documentation of related events. Currently available paper headache diaries are not standardized. Standardized diaries would require lengthy symptom lists and other information resulting in complex daily forms, unsuitable for many applications. Electronic diaries have the advantage of including complex information in an easy-to-use format, and greatly reducing data management activities. There are currently no commercially available electronic headache diaries. The purpose of this proposal is to develop a standard electronic headache diary to collect detailed information about daily headache episodes and related events. Software will be developed for a hand-held computer. Programmed skip sequences will reduce subject burden. Build-in validation checks, reminders, and a log to record the time of data entry will improve data quality. Separate data coding and entry is eliminated, and meaningful data summaries can be easily generated. During Phase I, we will design and develop software specifications for the electronic headache diary, develop a prototype, and conduct a pilot evaluation. During Phase II, we will develop a marketable product and conduct a full-scale evaluation. PROPOSED COMMERCIAL APPLICATION An electronic headache diary can be used for any clinical or research application where daily information on headaches and related events is needed. Possible markets include headache clinics, primary care facilities, universities, research firms, and the pharmaceutical industry. Severe headaches are experienced by at least 45 million Americans yearly, resulting in over 12 million ambulatory care visits. Beyond use in research studies and at medical clinics, and electronic headache diary has a strong potential over-the-counter market.